This invention relates to a bushing assembly employed in an engine mount. More particularly, this invention relates to an improved bushing assembly having a pair of nesting, cup-shaped housings.
A typical three-point engine support system comprises a pair of trunnions positioned on opposite sides of the engine for mounting the aft end thereof on a vehicle frame. Since the engine mount for each trunnion is subjected to dynamic forces during vehicle operation, a rubber support bushing is normally utilized therein to deter the transmission of such forces from the frame to the engine. Although the support bushing substantially absorbs forces acting radially relative to the trunnion, the bushing does not adequately isolate forces transmitted axially therealong.
Since the rubber bushing is structurally weaker and exhibits a lower spring rate in shear than in compression, the engine tends to become displaced transversely relative to the frame to induce engine drive train misalignment problems. As a result, the engine, flywheel housing and associated drive train components are severely stressed and are thus prone to failure. Such engine displacement further creates vibrational forces and associated noise, due to the metal-to-metal contact occurring between the support trunnion and the vehicle frame.
One solution to the above-cited problems is found in U.S. Pat. No. 3,770,231 to Kirchgessner et al, assigned to the Assignee hereof. However, certain difficulties may be encountered in assembling the tight fitting components in that a block or lock effect can be encountered when air is trapped within the space defined by the tight fitting components.